#!/bin/bash

# default_background Version 0.1

# Most of this code was from Eric Harrison's "K12LTSP-Backgrounds" code
# Original Source: ftp://k12linux.mesd.k12.or.us/pub/K12LTSP/testing/SRPMS/k12ltsp-backgrounds-0-0.src.rpm
# Some code originates from http://www.tldp.org/LDP/abs/html/
# Additional code by Jon Spriggs (jon {dot} spriggs {at sign} g {for google} mail {dot} com)

# Eric's code produced only a default background image. Because of the environment I'm trying to create
# I want to set either a mandatory image or colour plate (depending on whether the environment will be
# remote or local). As this is not yet defined for my environment, I'm taking a sledgehammer and nut.

# The original code has been modified to accept the following switches:
#
# --mandatory
# AKA -m
#
# --colour
# --color
# AKA -c
#
# --revert
# --remove
# --delete
# AKA -r
#
# Or, no switches which implies default only.

# Let's start with the code itself.

ROOT_UID=0 	# Only users with $UID 0 have root privileges.
E_NOTROOT=127 	# Non-root exit error.

# Run as root, of course.
if [ "$UID" -ne "$ROOT_UID" ]
then
	echo "You are not root. You must be root to run this script, otherwise it won't work. Sorry."
	exit $E_NOTROOT
fi

touch /etc/sysconfig/background/default.img

case "$1" in
	"")
		VAR1=
		;;
	*)
		VAR1=$1
		;;
esac
case "$2" in
	"")
		VAR2=
		;;
	*)
		VAR2=$2
		;;
esac
case "$3" in
	"")
		VAR3=
		;;
	*)
		VAR3=$3
		;;
esac
case "$4" in
	"")
		VAR4=
		;;
	*)
		VAR4=$4
		;;
esac
case "$5" in
	"")
		VAR5=
		;;
	*)
		VAR5=$5
		;;
esac

SETORUNSET=set

ProcessVariables () {
	case "$1" in
	--help)	
		showusage
		;;
	--usage)	
		showusage
		;;
	-m)
		MANDATORY=TRUE
		;;
	--mandatory)
		MANDATORY=TRUE
		;;
	--revert)
		SETORUNSET=unset
		;;
	--remove)
		SETORUNSET=unset
		;;
	--delete)
		SETORUNSET=unset
		;;
	-r)
		SETORUNSET=unset
		;;
	"")	
		return 1
		;;
	*)
		FILEORCOLOUR=$1
		;;
	esac
}

showusage () {
	echo "`basename $0` {-m | -r} (file)"
	echo "-m Sets a mandatory background"
	echo "-r Removes a mandatory or default background"
	echo "If used with no switches, this will produce this screen"
	echo "If a filename only is provided, then this file will be used as the default background"
	exit 255
}

ProcessVariables $1
ProcessVariables $2
ProcessVariables $3
ProcessVariables $4
ProcessVariables $5

if [ ! "$FILEORCOLOUR" ]
	then
		showusage
		exit 0
fi

echo $SETORUNSET $FILEORCOLOUR \(Mandatory? $MANDATORY\)

if [ -f "$FILEORCOLOUR" ]
	then 
		COLOUR=FALSE
	else
		COLOUR=TRUE
fi

if [ `echo "$COLOUR" | grep "FALSE"` ]
then
	# is it an image file?
	IMAGE=`file $FILEORCOLOUR | cut -d":" -f2- | grep -i image`
	if [ ! "$IMAGE" ]
		then 
			showusage
	fi
fi


if [ `echo "$SETORUNSET" | grep "set"` ]
	then
		mv /etc/sysconfig/background/default.img  /etc/sysconfig/background/default.img.last 
		cp "$FILEORCOLOUR" /etc/sysconfig/background/default.img
		chown root:root /etc/sysconfig/background/default.img
		chmod 0644 /etc/sysconfig/background/default.img
fi

if [ `echo "$MANDATORY" | grep "TRUE"` ]
	then
		gconftool-2 --direct --type string \
			--config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
			--$SETORUNSET /desktop/gnome/background/picture_filename /etc/sysconfig/background/default.img
	else
		gconftool-2 --direct --type string \
			--config-source xml:readwrite:/etc/gconf/gconf.xml.defaults \
			--$SETORUNSET /desktop/gnome/background/picture_filename /etc/sysconfig/background/default.img
fi